scholarly journals Declining populations of mountain yellow-legged frogs: a reassessment of the evidence implicating pesticides

2015 ◽  
Author(s):  
J. Marohasy ◽  
J. Abbot
Keyword(s):  
Declining Populations

scholarly journals Are declining populations of wild geese in China ‘prisoners’ of their natural habitats?

2017 ◽  
Vol 27 (10) ◽  
pp. R376-R377 ◽  
Author(s):  
Hui Yu ◽  
Xin Wang ◽  
Lei Cao ◽  
Lu Zhang ◽  
Qiang Jia ◽  
...  
Keyword(s):  
Natural Habitats ◽  
Declining Populations

Reproductive Failure in Populations of the Dog-Whelk, Nucella Lapillus, Caused by Imposex Induced by Tributyltin from Antifouling Paints

1986 ◽  
Vol 66 (4) ◽  
pp. 767-777 ◽  
Author(s):  
P. E. Gibbs ◽  
G. W. Bryan
Keyword(s):  
Vas Deferens ◽  
Early Stage ◽  
Premature Death ◽  
Intermediate Stage ◽  
Reproductive Failure ◽  
Nucella Lapillus ◽  
Egg Capsules ◽  
Male Characters ◽  
High Incidence ◽  
Declining Populations

The development of male characters, notably a penis and a vas deferens, on the female (the phenomenon of ‘imposex’) of the dog-whelk, Nucella lapillus, is described. Three stages are recognized: an ‘early’ stage involving the formation of a vas deferens and a small penis, an ‘intermediate’ stage characterized by the enlargement of the female penis to a size approaching that of the male and a ‘late’ stage during which the female opening (vulva) is occluded by overgrowth of vas deferens tissue. This blockage of the pallial oviduct prevents the release of egg capsules and renders the female sterile. The extent and cause of such reproductive failure is evident from the high incidence of females containing aborted capsules in declining populations close to sources of tributyltin (TBT) contamination. These same populations comprise fewer females than expected and it would appear that the accumulation of aborted capsules within the pallial oviduct eventually causes the premature death of the female.

scholarly journals How many bird extinctions have we prevented?

Oryx ◽  
2006 ◽  
Vol 40 (3) ◽  
pp. 266-278 ◽  
Author(s):  
Stuart H.M. Butchart ◽  
Alison J. Stattersfield ◽  
Nigel J. Collar
Keyword(s):  
Invasive Species ◽  
Captive Breeding ◽  
Extinction Risk ◽  
Bird Species ◽  
Iucn Red List ◽  
Additional Species ◽  
Conservation Actions ◽  
Declining Populations ◽  
Population Sizes ◽  
Principal Actions

Considerable resources and efforts have been directed at biodiversity conservation in recent years, but measures of the success of conservation programmes have been limited. Based on information on population sizes, trends, threatening processes and the nature and intensity of conservation actions implemented during 1994–2004, we assessed that 16 bird species would have probably become extinct during this period if conservation programmes for them had not been undertaken. The mean minimum population size of these 16 species increased from 34 to 147 breeding individuals during 1994–2004. In 1994, 63% of them had declining populations but by 2004, 81% were increasing. Most of these species (63%) are found on islands. The principal threats that led to their decline were habitat loss and degradation (88%), invasive species (50%) and exploitation (38%), a pattern similar to that for other threatened species, but with exploitation and invasive species being relatively more important. The principal actions carried out were habitat protection and management (75% of species), control of invasive species (50%), and captive breeding and release (33%). The 16 species represent only 8.9% of those currently classified as Critically Endangered, and 1.3% of those threatened with extinction. Many of these additional species slipped closer to extinction during 1994–2004, including 164 that deteriorated in status sufficiently to be uplisted to higher categories of extinction risk on the IUCN Red List (IUCN, 2006). Efforts need to be considerably scaled up to prevent many more extinctions in the coming decades. The knowledge and tools to achieve this are available, but we need to mobilize the resources and political will to apply them.

scholarly journals Are orchid bees at risk? First comparative survey suggests declining populations of forest-dependent species

2013 ◽  
Vol 73 (2) ◽  
pp. 367-374 ◽  
Author(s):  
A Nemésio
Keyword(s):  
Atlantic Forest ◽  
Anthropogenic Disturbances ◽  
The Other ◽  
Orchid Bees ◽  
Orchid Bee ◽  
Disturbed Areas ◽  
Eastern Brazil ◽  
Forest Remnants ◽  
Declining Populations ◽  
Comparative Survey

The two largest Atlantic Forest remnants in the state of Espírito Santo, eastern Brazil, namely ‘Reserva Biológica de Sooretama’ (REBIO Sooretama) and ‘Reserva Natural Vale’ (RNV), were surveyed for their orchid-bee faunas. Seventeen scent baits were used to attract orchid-bee males. Three-thousand, two hundred and twenty-five males belonging to 24 species were actively collected with insect nets during 100 hours in March, April and December, 2009. In comparison with a previous study in the same area twelve years before, it is evident that the abundance of all forest-dependent orchid bees analysed declined around 50%, and it was statistically significant (P = 0.022) for Euglossa marianae Nemésio, 2011, the most sensitive to anthropogenic disturbances of all Atlantic Forest orchid bees. On the other hand, the abundance of populations of species tolerant to open or disturbed areas rose. Possible explanations are discussed.

scholarly journals A wood-warbler produced through both interspecific and intergeneric hybridization

2018 ◽  
Vol 14 (11) ◽  
pp. 20180557 ◽  
Author(s):  
David P. L. Toews ◽  
Henry M. Streby ◽  
Lowell Burket ◽  
Scott A. Taylor
Keyword(s):  
Intergeneric Hybridization ◽  
Population Declines ◽  
Morphometric Traits ◽  
Early Generation ◽  
Phenotypic Differences ◽  
Vermivora Chrysoptera ◽  
Hybridization Event ◽  
Wood Warblers ◽  
Declining Populations ◽  
Female Hybrid

Hybridization between divergent taxa can provide insight into the breakdown of characters used in mate choice, as well as reproductive compatibility across deep evolutionary timescales. Hybridization can also occur more frequently in declining populations, as there is a smaller pool of conspecific mates from which to choose. Here, we report an unusual combination of factors that has resulted in a rare, three-species hybridization event among two genera of warblers, one of which is experiencing significant population declines. We use bioacoustic, morphometric and genetic data, to demonstrate that an early generation female hybrid between a golden-winged warbler ( Vermivora chrysoptera ) and a blue-winged warbler ( V. cyanoptera ) went on to mate and successfully reproduce with a chestnut-sided warbler ( Setophaga pensylvanica ) . We studied the product of this event—a putative chrysoptera × cyanoptera × pensylvanica hybrid—and show that this male offspring sang songs like S. pensylvanica , but had morphometric traits similar to Vermivora warblers. The hybrid's maternal parent had V. chrysoptera mitochondrial DNA and , with six plumage-associated loci, we predicted the maternal parent's phenotype to show that it was likely an early generation Vermivora hybrid . That this hybridization event occurred within a population of Vermivora warblers in significant decline suggests that females may be making the best of a bad situation, and that wood-warblers in general have remained genetically compatible long after they evolved major phenotypic differences.

scholarly journals Re-orientating the Experience of a Small Town

2021 ◽  
Author(s):  
◽  
Katherine Hailstone
Keyword(s):  
Urban Landscape ◽  
Social Issues ◽  
Traditional Approach ◽  
Small Towns ◽  
Design Approach ◽  
Master Plan ◽  
Large Cities ◽  
Aging Populations ◽  
Declining Populations ◽  
The Town

<p>An experience by definition can imply that it leaves an impression. It can be how people experience our small towns that influence its viability and success. Small towns in Aotearoa face aging populations, growing social issues and tend to lack economic viability. Current statistics show population growth in our large cities and declining populations in our regions impacting the urban landscape and the experience of our regional towns. So, how can designing from an experiential approach make a difference to town life?  A traditional approach to changing the experience of towns and cities is through consultation, a production of a master plan and then staging the design over time. Consider what could be gained if we used on-the-ground experience to inform the structure our towns?  If we intensely engage with the ‘on the ground experience’ of the town, looking at how the town structures experience, we should be able to identify opportunities that could re-orientate how people interact with the town. These opportunities or potential design alterations, could reshape the way that the town is structured and therefore inform the development of a master plan or long term plan. Through an experience-based design approach the opportunities that can be identified from this method are often not visible from other techniques such as top down mapping and other common forms of data collection. Through a combination of; an understanding of the experience of the town, its history, influences, though various forms of mapping and the understanding the viability of proposed design alterations we could strategically transform the experience.  Therefore, through an experiential design approach and understanding how our small towns work in Aotearoa; can we focus design actions in the public environment to develop potential future change?</p>

The Decline of Small Communities

2011 ◽  
Author(s):  
Robert Wuthnow
Keyword(s):  
Small Towns ◽  
Small Communities ◽  
Declining Populations ◽  
Middle West ◽  
The Military

This chapter examines the decline of small communities in the Middle West. In 1980, 76 percent of all the incorporated towns and cities in the Middle West had fewer than 1,500 people. The region's nine states ranked first through ninth nationally (not counting Alaska) in having the highest proportion of small towns this size. These figures indicate that the Middle West was defined by its small communities. The chapter considers the changing size of communities in the Middle West, focusing on how small towns were being affected by and responding to stable or declining populations. It also explores three factors that influenced the trajectory of Middle Western towns: oil, agriculture, and the military. Finally, it discusses the efforts of residents of small communities to keep their towns as livable and attractive as possible.

Advances in Fish Tagging and Marking Technology

2012 ◽  
Keyword(s):  
Atlantic Salmon ◽  
Salmo Salar ◽  
Release Time ◽  
Tag Identification ◽  
Penobscot River ◽  
Salmon Population ◽  
Declining Populations ◽  
Simple Change ◽  
Using Data ◽  
Made In

<i>Abstract</i>.—Atlantic salmon <i>Salmo salar </i>smolts are stocked in the Penobscot River, Maine to supplement declining populations. Since 2000, approximately 550,000 hatchery smolts are annually released into the river, of which 32% of these (175,000) were marked with visual implant elastomer (VIE) tags indicating release time and location. Our study found that tag colors of adult returns were often misread due to confusion between green and yellow marks and between red and pink marks. Using data collected on mark readings in a controlled hatchery environment, we corrected for tag identification errors made in the field, thereby allowing adjustments to be made in the marked returns to accurately assess the number of returns from multiple stocking groups. When adult returns from multiple stocking groups were compared, significant differences were detected between stocking groups, including a three-fold difference between two of the stocking groups. Hence, a simple change in smolt stocking locations and times may be of value in the recovery of the Penobscot River salmon population.

Extending Educational Opportunities in Rural Areas

2010 ◽  
pp. 276-294
Author(s):  
Wallace Hannum ◽  
Matthew Irvin ◽  
Claire de la Varre
Keyword(s):  
United States ◽  
Distance Education ◽  
Rural Communities ◽  
Rural Schools ◽  
Rural Areas ◽  
The United States ◽  
Further Education ◽  
Educational Opportunities ◽  
Qualified Teachers ◽  
Declining Populations

Rural schools in many countries face problems in providing educational opportunities to children and youth for a variety of reasons. There has been the tendency in many countries to migrate to urban areas, often in search of better economic opportunities. The resulting shift from rural areas to urban/suburban areas has placed increased pressures on schools in rural communities. Schools often form the hub of social and civic activity in rural communities. Although they are an important component to rural communities, many rural schools are struggling under the weight of declining populations, declining budgets, staffing difficulties, and increased pressures to better prepare students for the workforce or further education. Rural schools face particular difficulties in attracting and retaining qualified teachers. Faced with problems of providing a comprehensive curriculum and qualified teachers, many rural schools in the United States have turned to distance education. This case explores the use of distance education in the United States through a national survey of distance education use, analysis of barriers to distance education and an experimental study of enhancing distance education through more appropriate training of local facilitators to support students.

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